Visitor or Temporary Resident Visa While Waiting for PR

[rachel6992]

I think I already know the answer to this, but thought I'd ask anyway...

We're waiting for our PR to go through (family class/common-law, being processed in Mexico City).  Right now my partner and I live in the US, but he has overstayed his visa here.  He doesn't really have a life in Mexico anymore, as he was brought here by his parents when he was a child.  I know that the immigration officers will check for that.  If I go to Canada to get settled in while the application is in process, can he file for a visa to come and stay for a couple of months until he is called for an interview in Mexico?  It seems that this is highly unlikely, but any tips would be helpful!

Thanks!